1. Field of the Invention
This invention relates generally to tracked vehicles, and particularly to a cycle having a rear track for providing the driving force and a front ski for steering the cycle.
2. Discussion of the Prior Art
Track-driven cycles have been designed based upon the standard bicycle frame and using many of the same components. For example, French Patent Publication 2,556,303, published in 1985, discloses the adaptation of a conventional bicycle frame to a track wherein the front fork, instead of receiving a wheel, is coupled to an A-frame attached to a ski. In another example, illustrated in U.S. Pat. No. 3,915,468, a bicycle-type frame is mounted to a track assembly. In 1900, U.S. Pat. No. 654,291 issued which also disclosed a bicycle frame having front and rear tracks.
Each of the foregoing tracked cycles suffer from disadvantages which render them impractical or unworkable. The French design is simply an adaptation of a road bicycle frame which is inherently weak, particularly in the front fork design. The lower end of the front fork, coupled to the top of the ski A-frame does not have sufficient rigidity to withstand torsional stresses. Moreover, the track assembly does not provide sufficient rise in the leading edge to climb above snow or mud deeper than the height of the track. With respect to the device disclosed in the '468 patent, a conventional bicycle front fork is also used, which does not accommodate torsional stresses in the horizontal plane produced by the ski. Furthermore, the track assembly is fairly complicated and bulky, which increases the weight of the vehicle making it difficult to power manually. Additionally, the low profile of the frame and the location of the crank shaft and pedals results in the user's feet often in the snow or mud, making pedaling difficult. The device disclosed in the '291 patent publication also suffers from many of the same aforementioned problems, but also employs an extremely complicated tracking system requiring many moving components. This latter system is extremely heavy, costly to manufacture, and inordinately difficult to power, particularly when debris encrusts the race about which the track runs.